It is well known to use particles to modify the surface of cotton fibres. Consequently, particulate inorganic materials such as clays, silica and alumino-silicate have been widely used in detergent compositions. Typically, these are present as ‘softeners’ which associate with the surfaces of fibres and fibrils of cotton.
In recent years it has been proposed to use so-called ‘nanoparticles’ for fabric treatment. WO 02/064877 (P&G) discloses coating compositions, which comprise a ‘nanoparticle’ system of a size of less than or equal to 750 nm, with a lower limit of ‘0’ nm. Examples provided include synthetic silica (10–40 nm), boehemite alumina (2–750 nm) and ‘nanotubes’ (2–50 nm). Clays, particularly plate-like laponites (25–40 nm wide and ˜1 nm thick) are considered suitable and organic materials such as nano-latexes are proposed.
Nanosilica particles are negatively charged and are not expected to deposit on the fabric surface (also negatively charged) during wash because of their negative charge. At pH 8, for example, the Zeta-potential of a nanosilica was measured to be −21 mV.
EP 1371718 (Rohm and Haas) discloses 1–10 nm polymeric nanoparticles as a fabric care additive. These can be organically modified with silicones.
WO 02/18451 (Rhodia) discloses the use of nanoparticles in a polymeric or nano-latex form.
DE 10248583 (Nanogate Technologies GmbH) discloses the use of inorganic nanoparticles as a carrier for a silane material.